[Ffmpeg-devel] MPEG-1 Decoder

[Michel Bardiaux]

Matthew Gertner wrote:
> Nico,

Please dont top-post.

> 
> I'd be fascinated to find out more about how media files are 
> multiplexed, but realistically this is far out of my area of expertise 
> so the learning curve is likely to be steep. On Francois's suggestion I 
> posted a truncated version of the naughty file here: 
> http://www.allpeers.com/blog/downloads/MPEG-1%20Issue.mpg.
> 
> Perhaps someone with the necessary expertise will be interested enough 
> to take a look.

I have run the file thru a demuxer of mine that is designed to follow 
the MPEG standard very strictly rather than be effective and permissive 
as mplayer is. The diagnostic is clear:

*** expect_bits: horoMpkCorruptionError: Expecting 0000 0000 0000 0000 
0000 0001 1011 1010 at bitpos 0, got 0101 0010 0100 1001 0100 0110 0100 0110

This is definitely not a standard MPEG-1 system stream (aka PS). How was 
the file encoded in the first place?

> 
> Cheers,
> Matt
> 
> Nico Sabbi wrote:
> 
>> Matthew Gertner wrote:
>>
>>> Nico,
>>>
>>> Yep, MPlayer is able to read the file even when forced to use the 
>>> ffmpeg codecs, which I presume confirms that libavcodec is not at 
>>> fault, as you surmised. If the demuxer is the problem, is there some 
>>> workaround for this? What can I do to make sure that we can decode 
>>> this type of file?
>>>
>>> Cheers,
>>> Matt
>>>
>> there are no tricks that I know of. You can either fix the demuxer and 
>> send the patch to this list or
>> use a different demuxer. In the long run lavf should become the 
>> preferred/only demuxer library in some
>> projects, so fixing it is surely preferrable
>>

-- 
Michel Bardiaux
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